Hardeners for photographic gelatin

ABSTRACT

Compounds represented by the general formula,   (Wherein R is hydrogen or a methyl group and X is a lower alkylene group of 1 to 6 carbon atoms) are effective gelatin hardeners.

United States Patent [191 Horii et al.

[4 1 Feb. 25, 1975 21 Appl. No.: 319,025

[30] Foreign Application Priority Data Dec. 30, 1971 Japan 47-2346 [52] US. Cl 96/111, 96/100, 260/117, 106/125 [51] Int. Cl G03c 1/30 [58] Field of Search 96/111, 100; 260/117; 106/125 [56] References Cited UNITED STATES PATENTS 3,455,892 7/1969 Froehlich 96/111 3,490,911 l/1970 Burness et al. 96/111 Primary ExaminerNorman G. Torchin Assistant ExaminerWon H. Louie, Jr. Attorney, Agent, or Firm-Cushman, Darby & Cushman [57] ABSTRACT Compounds represented by the general formula,

CH 1 CH S0 CH CHCONH\ CH SO CH CHCONH (Wherein R is hydrogen or a methyl group and X is a lower alkylene group of l to 6 carbon atoms) are effective gelatin hardeners.

7 Claims, No Drawings 1 HARDENERS FOR PHOTOGRAPHIC GELATIN The present invention relates to hardeners for photographic gelatin and a method for hardening a gelatincontaining photographic layer.

It has been well known that mechanical strength of photographic layer can be increased and resistances against dissolution, swelling and separation of the layer during photographic processes can be improved by adding a gelatin hardener capable of cross linking physically or chemically with gelatin in preparation of the gelatin-containing photographic layer. A number of compounds have been proposed for gelatin hardeners; Among them, the following compounds have been known to be especially effective; i.e., formalin, mucochloric acid, addition products of formalin, nitrogencontaining heterocyclic six membered ring compounds having two or more of active halogens in the molecule for instance, 2,4-dichrolo-6-B-hydroxyethylaminel,3,5.-triazine, compounds having active vinyl groups such as divinyl sulfone, divinyl ketone, N,N,N- triacryloylhexahydro-1,3,5-triazine, compounds containing two or more of aziridine groups or epoxy groups in the molecule and high molecular hardeners such as dialdehyde starch, polyvinyl alcohol and maleic acid half esters of starch, etc. However, these compounds cannot provide satisfactory results in gelatin-containing photographic layer. Even formalin which has been most commonly used has many defects, e.g., the hardening is difficult to control to a desired degree due to the so called post-hardening phenomenon which means 7 gradual hardening caused even at later stage, it tends to result in fog in emulsion and when used in color photographic emulsion, it reacts with color coupler to cause reduction in sensitivity or abnormal color coupling. Regarding other hardeners, some cause coloration of photographic layer and some cause conspicuous changes in hydrogen ion concentration of emulsion with progress of hardening to result in deterioration of photographic properties. Furthermore, some of them have pungent smell to reduce operability in preparation of are harmful for human body. Although, there are many compounds which are photographically not harmful and preferable, but many of them are expensive or require complicated procedures to apply them, e.g., they have to be dissolved in an organic solvent and then dispersed in an emulsion.

It has also been well known that hardeners having active vinyl group can be advantageously used for this purpose. For example, German Pat. No. 872,153 (1949) discloses use of divinyl sulfone, but this compound has strong irritating property and toxicity to human body. Furthermore, German Patent Publication No. 1,100,942 (1961) has proposed aromatic compounds having two or more of vinylsulfonyl groups in the molecule and US. Pat. No. 3,490,911 (1970) has proposed compounds having vinylsulfonylethyl groups.

The characteristics of these vinyl sulfone type hardeners are as follows: they have rapid hardening action and the so-called posthardening occurs with difficulty, the so-called over-hardening phenomenon (hardening proceeds to much and photographic emulsion film hecomes keratin (becomes brittle) to damage the permeability of processing solution) occurs in low frequency; photographically undesirable actions such as fog, stain or ground, etc., less occur; and the suppression of color development or discoloration caused by reactions with color couplers are not caused. Therefore, the vinyl sulfone type hardeners are excellent in these points, but most of them are too much expensive and moreover some of them require a large amount of organic so|- vents in their application or the amount of addition must be limited to avoid troubles caused by change in viscosity with lapse of time. Under the circumstances, such vinyl sulfonyl compounds as easily prepared and required no specific procedure for application have been much demanded.

One object of the present invention is to provide effective hardeners for photographic gelatin and for gelatin-containing photographic emulsions. Another object of the present invention is to provide a method for effectively hardening a gelatin-containing photographic layer. Other object ofthe present invention will appear herein.

The inventors have found that use of the compounds represented by the following general formula can completely overcome the difficulties of the conventional hardeners.

R l CH=OH-SO-CH-CH-CONH \X CH=CHSO-CH-CHCONH/ (Wherein R is hydrogen or methyl group and X is a lower alkylene group of l to 6 carbon atoms).

When these compounds are incorporated into gelatin-containing photographic emulsion, such undesired phenomena as photographic deteriorations such as fog. desensitization, coloration of ground, discoloration, change of hydrogen ion concentration of the emulsion, reactions with color couplers, etc., are hardly observed and these hardeners maintain rapid hardening property of the compounds having vinyl sulfonyl groups in common and moreover no so-called post-hardening phenomenon occurs. Therefore, the photographic emulsion layer can be very easily hardened to the desired degree. Furthermore, the change of viscosity of the photographic emulsion during preparation is surprisingly minor as compared with that of the case of other vinyl sulfonyl compounds being used and this is the important characteristic of the compounds used as hardeners of the present invention. These compounds have further characteristics that they are excellent in affinity with water and require no special organic solvent in their application, being different from the other conventional vinyl sulfonyl compounds. Furthermore, the compounds of the present-invention are also superior to the conventional vinyl sulfonyl compounds in that they have substantially no bad effect on human body due to gasification and cause less physiological action to the skin.

It seems that most ofthese excellent properties of the compounds used as hardeners in the present invention which are not possessed by the conventional vinyl sulfonyl compounds are attributable to the action of amide groups in the structure. Because of the strong polarity of said group, the volatility of the compounds is restrained, the affinity to water is increased and the affinity to lipids is lost whereby the toxicity is lowered. Furthermore. since the compounds of the present invention have structure very similar to that of gelatin, there is a little difference in properties between hardened part and unhardencd part of the emulsion and the (LII) (VII) photographic emulsion in which the compounds of the present invention are used shows no great difference in viscosity before and after hardening. The amount in Examples of the compounds especially suitable in the present invention are shown below.

= OH SO CH CH CO NH /CH2 CH2 CH SO2.-'CH2 CH2 o0 NH CH2 CH s02 0 CH2 co NH THZ CH2 CH so CH2 CH2 co NH CH2 a CH s0 CH2 CH2 c0 NH :H cs

: 0H s0 CH2 CH2 co NH CH2 CH s0 CH2 CH2 co NH-\\\\ cH CH s0 CH2 CH2 co NH CH s0 CH2 0H c0 NH\\\\\ 2 4 CH so CH2 CH2 co NH CH so CH2 CH2 00 H cH CH so CH2 CH2 c0 NH e CH so CH2 CH co NH\\\\\ CH2 CH'- so CH2 CH 00 NH These compounds can be prepared, for example, by dized or firstly B-hydroxyethylthio group is oxidized to dehydrochlorination of the following compound (B).

I on CH2 CH2 so CH2 CH c0 NH convert it into B-hydroxyethyl sulfonyl group and then (wherein R and X are the same as defined in the compound (A) Besides the above method, the compound (A) will be produced from compounds similar to the compound (8) by known methods of introducing vinyl group.

The B-chloroethyl sulfonyl groups can be introduced as follows:

a, B-Unsaturated fatty acid derivatives and B-chrolo ethane sulfinic acid are reacted to produced compounds having the said group, or hydroxyl groups of B-(B-hydroxylethylthio) fatty acid derivatives produced by reactions of B-mercaptoethanol and B-unsaturated fatty acid derivatives are firstly converted to the chrologroups and then its thioether bond is oxihydroxyl group is chlorinated into above mentioned minutes. The temperature was decreased to C and stirring was carried out for 1 hour and thereafter the separated crystal was filtered off. To the filtrate while stirring at 5 C was added a solution of 7.1 g of acrylamide in 50 ml of water and they were preserved at cold state for 48 hours. The separated crystal was filtered and washed with a small amount of cold water and recrystallized from methanol giving 12 g of colorless crystal having a melting point of 137.5 138.5C. Preparation 2 N,N-methylenebis-lB-(B-chloroethylsulfonyl) propionamide] A mixture of 4 g of a-(a-chloroethylsulfonyl) propionamide obtained in Preparation 1 and 0.6 g of paraformaldehyde was heated in an oil bath at 110C and 4 drops of concentrated sulfuric acid were added thereto. Thereafter, the bath temperature was gradually raised to 150 155C and reaction was effected for 1.5 hour. After the reaction product was allowed to volatile hardening substance such as formalin at a coverage of 1.25 g./m of silver in terms of silver nitrate and 3 g./m of gelatin and thus coated paper was dried.

Some of these samples were stored for 2 days at room temperature and others under acceleration condition of 50C and 80 RH for 2 days. Thereafter, each of the samples were exposed through a step wedge, processed for 2 minutes at 20C in Kodak D-72 1 2) developer, fixed and washed with water. Sensitivity and fog density of these samples were measured. Furthermore, each sample was dipped in 4 percent aqueous s0- lution of Na CO .H O for 3 minutes at 20C and then a ball point pen having a ball diameter of 1 mm was perpendicularly set on film of the sample emulsion. Then, the sample was horizontally moved at 1 cm/sec. and the minimum load of the ball point pen (referred to as film strength hereinafter) which caused detectable damages on the film of the emulsion was measured. The results are shown in the following Table 1.

Table 1 stand for cooling, water was added thereto and insoluble matter was filtered and, recrystallized from water to obtain 2.4 g. of colorless crystalline powder having a melting point of 2l3.0 214.0C. Preparation 3 N.Nmethylene bis-91HB-chlorocthylsulfonyl) propionamide) was dispersed in 250 ml of dimethylformamide and added thereto with stirring was 4.44 g. of triethylamine at room temperature. The stirring was continued for 5 hours and then the undissolved matter was filtered off. To the filtrate was added 50 ml of toluene and the mixed solution was concentrated under a reduced pressure into ajelly-like product of considerably high viscosity, to which ml of benzene was added to separate crystal. The crystal was filtered off and was washed with a small amount of ethanol and then was recrystallized from ethanol to obtain 5.5 g. of the desired product having a melting point of 147.0 148.0C.

Elementary Analysis: for CnH1gN-ZO6S2 C H N Calcd. (71) 39.04 5.36 8.28 Found (1) 39.15 5.47 8.11

The present invention is further illustrated by the following examples of preferred embodiments thereof.

EXAMPLE 1 'by polyethylene coating and which contained no From the above Table 1, it is clearly recognized that a gelatin-containing photographic emulsion layer which was hardened in a short period of time after coating and showed no over-hardening under acceleration conditions was obtained without causing any undesirable effect on sensitivity and fog density.

Changes of viscosity of thus obtained emulsions with lapse of time were measured with the following results.

It is surprising that according to the method of the present invention, no substantial change in viscosity of emulsion is caused during storage.

EXAMPLE 2 Each of the following hardeners was added to four separate portions of the silver bromoiodide emulsion prepared in the same manner as in Example 1 in a proportion of 2 g. of the hardener per g. of gelatin.

a. The compound obtained in said Preparation 3 b. Formalin c. Hardener D 11 S (Trade name of a vinyl sulfon hardener manufactured by Carbic Hoechst Corp.)

d. N,N'.N"-triacryloylhexahydro-1.3.5-triazine Each of the sample emulsions was coated on the same RC base paper as used in Example 1 at a coverage of 1.25 g./m of silver (in terms of silver nitrate) and 3 g./m of gelatin. A sample of each film coating was then dried and cured under conditions of 20C 58 RH and 50C 80 7r RH each of them using saturated solution of NaBr. 2H O and Kcl. Film strength of each sample was measured in the same manner as in Example I with the The above results indicate that when the hardener of the present invention was used, the gelatin was hardened to the desired degree in a short period of time after application and post-hardening phenomenon during storage hardly occurred.

According to these results, the rapid hardening action of the hardener of the present invention is comparable to that of the compound (c) and superior to the compound (b) as well as the compound (d).

Compound (a) can be used as a 1 percent aqueous solution, but compound (c) must be added to emulsion as 1 percent DMF solution or 1 percent dioxane solution.

EXAMPLE 3 Example I was repeated except that the compound obtained in Preparation 3 was replaced by compound (lV) listed before to obtain the same results as Example I.

EXAMPLE 4 Example 1 was repeated except that the compound obtained in Preparation 3 was replaced by compound (Vll) listed before to obtain the same results as those of Example 1.

EXAMPLE 5 ca ca so CH CHCONH \X en CH S0 CH (IZHCONH (Wherein R is a member selected from the group consisting of hydrogen and methyl group and X is a lower alkylene group 1 to 6 carbon atoms).

2. A gelatin-silver halide photographic emulsion containing as a hardener therein a compound having the general formula:

I OH CH s0 CH2 cacoma \X CH2 CH so CH2 CHCONH l ca ca s0 CH2 CHCONH en so,- ca cnconn (Wherein R is a member selected from the group consisting of hydrogen and methyl group and X is a lower alkylene group of l to 6 carbon atoms).

4. A composition according to claim 1, wherein the amount of the hardener is 0.1 20 percent by weight of gelatin based on the dry weight.

5. An emulsion according to claim 2 wherein the amount of the hardener is 0.1 20 percent by weight of gelatin based on the dry weight.

6. An emulsion according to claim 3 wherein the amount of the hardener is 0.1 20 percent by weight of gelatin based on the dry weight.

7. A method for hardening a gelatin-silver halide photographic emulsion, characterized in that a hardener having the general formula:

(Wherein R is a member selected from the group consisting of hydrogen and methyl group and X is a lower alkylene group of l to 6 carbon atoms) is allowed to be present in contact with the gelatin and hardening the gelatin with said hardener. 

1. A COMPOSITION OF MATTER COMPRISING GELATIN AND A HARDENER OF THE FORMULA:
 2. A gelatin-silver halide photographic emulsion containing as a hardener therein a compound having the general formula:
 3. A gelatin-silver halide photographic emulsion for use in color photography containing a coupler and as a hardener therein a compound having the general formula:
 4. A composition according to claim 1, wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
 5. An emulsion according to claim 2 wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
 6. An emulsion according to claim 3 wherein the amount of the hardener is 0.1 - 20 percent by weight of gelatin based on the dry weight.
 7. A method for hardening a gelatin-silver halide photographic emulsion, characterized in that a hardener having the general formula: 